Hoatzin

The Hoatzin (Opisthocomus hoazin) is a primitive chicken-sized bird of
South American swamps, principally in the Amazon and Orinoco river
basins. The young possess two large claws on each wing, a trait that
has led some scientists to link the species with the fossil
Archaeopteryx of the dinosaur era. The hoatzin is the only bird with a
digestive system that ferments vegetation as a cow does, which enables
it to eat leaves and buds exclusively. Hoatzins feed on swamp plants,
grinding foliage in a greatly enlarged crop (not the gizzard, as in
other birds). Adults can fly clumsily for short distances, but they
spend most of their time perched, digesting their leafy food. A large
rubbery callus on the bird’s breastbone acts as a tripod to keep it
from falling over when its stomach is distended.

The hoatzin is about 65 cm (25.6 inches) long but weighs less than 1
kg (2.2 pounds). It has a long tail, plumage streaked brown above and
yellowish below, a loose head crest, and a blue face with bright red
eyes. Sexes look alike, and both parents, as well as older siblings,
cooperate to raise two to five young. After four weeks of incubation,
the eggs hatch, and adults feed the chicks a leaf paste regurgitated
from the crop. Adult hoatzins hiss, hoot, and yelp at predators, such
as tayras and capuchin monkeys. Nests are built over water, and if
danger threatens, the young, which are excellent swimmers, will plunge
to safety, return to shore, and use their claws to climb back up to
the nest.

The hoatzin was first described scientifically in 1776 and has been
associated with several bird orders at various times since its
discovery. From its external features, it has been linked previously
to fowl-like birds of the order Galliformes. Although many authorities
presently classify the hoatzin with the cuckoos in the order
Cuculiformes, the hoatzin’s foot structure differs from that of other
members of the order. (Hoatzins have feet with three toes forward and
one behind, whereas cuckoos have feet with two toes forward and two
behind.) The hoatzin’s foot morphology combined with its unique
internal features have prompted some scientists to assign the hoatzin
to its own group, order Opisthocomiformes. Fossil evidence from France
suggests hoatzins may have lived over 36 million years ago, during the
Eocene Epoch. Hoatzins have existed in Colombia since the Miocene
Epoch, which began over 20 million years ago.

What a fascinating creature (a splendid photograph and informative write-up). Just look into those eyes. It's as if the creature is thinking: "Little do they know, my family goes back millions of years, long before the other upstarts round here. They were here with the Wyverns and Hippogriffs, in the days of Dragons and the giant Roc bird, and we have Phoenix blood in our veins. Ah, how the world has changed but we carry on, minding our own business, not upsetting anyone, and watching, watching ... because we know."

Thanks for the comments, everyone.I viewed this from a boat on Lake Sandoval. There were a pair of hoatzins, not fazed by our appearance - not that we got too close. I feel quite privileged to have seen them - I don't know if they're particularly rare in South America, but they're certainly the most unusual birds I've seen.

Though I've also seen a resplendant quetzal in Costa Rica - that was a privilege too. :-)